Extract method "createSessionWithCredentials"

This is a preparatory refactoring for a new feature that supports
authentication with user defined credentials.

Author: stefanbirkner

src/test/java/com/github/stefanbirkner/fakesftpserver/rule/FakeSftpServerRuleTest.java

@@ -895,10 +895,9 @@ private static Session connectToServer(
     private static Session connectToServerAtPort(
         int port
     ) throws JSchException {
-        Session session = JSCH.getSession(
-            "dummy user", "127.0.0.1", port);
-        session.setConfig("StrictHostKeyChecking", "no");
-        session.setPassword("dummy password");
+        Session session = createSessionWithCredentials(
+            "dummy user", "dummy password", port
+        );
         session.connect(TIMEOUT);
         return session;
     }
@@ -920,6 +919,17 @@ private static void connectAndDisconnect(
         session.disconnect();
     }
 
+    private static Session createSessionWithCredentials(
+        String username,
+        String password,
+        int port
+    ) throws JSchException {
+        Session session = JSCH.getSession(username, "127.0.0.1", port);
+        session.setConfig("StrictHostKeyChecking", "no");
+        session.setPassword(password);
+        return session;
+    }
+
     private static byte[] downloadFile(
         FakeSftpServerRule server,
         String path